Dry etching apparatus capable of monitoring motion of WAP ring thereof

Abstract

An optical monitoring system includes a ring-shaped object suspended by and engaged with a plurality of vertical plunger shafts. Normally, the vertical plunger shafts move upward and downward reciprocally and coherently, but independently, such that the ring-shaped object ascends or descends horizontally. A light transceiver device is affixed to one vertical plunger shaft. A plurality optical reflector elements are affixed to respective other plunger shafts. A light beam emanated from said light transceiver is reflected by the optical reflector elements and is eventually re-directed back to the light transceiver device.

1. An optical monitoring system for monitoring horizontal ascending or descending of a suspended ring-shaped or disk-shaped object, comprising:
 a ring-shaped or disk-shaped object suspended by and engaged with a plurality vertical plunger shafts, wherein, normally, said vertical plunger shafts move upward and downward reciprocally and coherently, but independently, such that said ring-shaped or disk-shaped object ascends or descends; 
 a light transceiver device affixed to one of said vertical plunger shafts; and a plurality optical reflector elements affixed to respective other said plunger shafts, wherein a light beam emanated from said light transceiver is reflected by said optical reflector elements and is eventually re-directed back to said light transceiver device. 
 
   
   
     2. The optical monitoring system according to  claim 1  wherein an alarm that is electrically connected to said light transceiver device. 
   
   
     3. The optical monitoring system according to  claim 2  wherein said alarm is triggered once an optical path between said light transceiver device and said optical reflector elements is interrupted. 
   
   
     4. The optical monitoring system according to  claim 1  wherein said optical monitoring system is electrically connected to a control unit that control said vertical plunger shafts. 
   
   
     5. The optical monitoring system according to  claim 1  wherein said light transceiver device comprises a laser diode transmitter and receiver. 
   
   
     6. The optical monitoring system according to  claim 1  wherein said light transceiver device comprises a light source and a light detector. 
   
   
     7. The optical monitoring system according to  claim 6  wherein said light source comprises laser, infrared light and light-emitting diode. 
   
   
     8. The optical monitoring system according to  claim 1  wherein said optical reflector element includes a mirror. 
   
   
     9. The optical monitoring system according to  claim 1  wherein said optical reflector element includes retro-reflective surface or adhesive-backed retro-reflective tape. 
   
   
     10. The optical monitoring system according to  claim 1  wherein said light transceiver device and optical reflector elements are substantially coplanar. 
   
   
     11. A dry etching apparatus capable of monitoring motion of a wafer-area-pressure (WAP) ring, comprising:
 a chamber housing encompassing an upper portion and a lower assembly, said upper portion further comprising said WAP ring encircling a top electrode; 
 plunger shafts engaging with said WAP ring, wherein said plunger shafts are connected to respective movable lower rollers that are bonded to corresponding fixed upper rollers by using a resilient means; 
 an annular cam reciprocally moves between said lower roller and said upper roller along a predetermined direction to protrude said WAP ring downward from said top electrode; and 
 an optical monitoring system comprising a light transceiver device and a plurality optical reflector elements affixed to respective said lower rollers or said plunger shafts, wherein a light beam emanated from said light transceiver is reflected by said optical reflector elements and is re-directed back to said light transceiver device. 
 
   
   
     12. The dry etching apparatus according to  claim 11  wherein said optical monitoring system further comprises an alarm that is electrically connected to said light transceiver device. 
   
   
     13. The dry etching apparatus according to  claim 12  wherein said alarm is triggered once an optical path between said light transceiver device and said optical reflector elements is interrupted. 
   
   
     14. The dry etching apparatus according to  claim 11  wherein said optical monitoring system is electrically connected to a control unit that control motion of said WAP ring. 
   
   
     15. The dry etching apparatus according to  claim 11  wherein said light transceiver device comprises a laser diode transmitter and receiver. 
   
   
     16. The dry etching apparatus according to  claim 11  wherein said light transceiver device comprises a light source and a light detector. 
   
   
     17. The dry etching apparatus according to  claim 16  wherein said light source comprises laser, infrared light and light-emitting diode. 
   
   
     18. The dry etching apparatus according to  claim 11  wherein said optical reflector element includes a mirror. 
   
   
     19. The dry etching apparatus according to  claim 11  wherein said optical reflector element includes retro-reflective surface or adhesive-backed retro-reflective tape. 
   
   
     20. The dry etching apparatus according to  claim 11  wherein said light transceiver device and optical reflector elements are substantially coplanar. 
   
   
     21. The dry etching apparatus according to  claim 11  wherein said lower assembly comprises an electrostatic chuck (ESC) and a focus ring. 
   
   
     22. The dry etching apparatus according to  claim 11  wherein said resilient means includes a spring.